While I've been reading a lot about Bitcoin being widely accepted across the state, I haven't seen a whole lot of info on the transaction processes themselves. I have an Android-based Bitcoin wallet (the official one from bitcoin.org) on my Samsung Galaxy S6, and I'm trying to get a sense of what store owners and service providers are expecting for in-person purchases as I'm new to the whole process. Would the app wallet itself suffice for buying stuff (seeing as how it has transfer features) or should I be looking into Bitcoin debit cards (like Coinbase's Shift Card for example)?

On a related note, is Monero popular at all? I've become a fan of the increased transaction privacy vs Bitcoin and have been casually mining it on the side.

No Monero is not popular in use, but it is popular (probably for savings or dark web). There isn't a mobile Monero wallet currently (that I know of), as it uses a completely different type of blockchain and protocol than bitcoin and the rest. It requires a full node. It doesn't support SPV (thin clients).